The agency's announcement comes in response to a study by Consumer Reports that shows 12 brands of soda have varying levels of 4-methylimidazole - an impurity found in some caramel coloring.
The FDA says it has studied the use of caramel as a flavor and color additive for decades but will review new data on the safety of 4-methylimidazole. The agency did not provide details about the data.
"These efforts will inform the FDA's safety analysis and will help the agency determine what, if any, regulatory action needs to be taken," said FDA spokeswoman Juli Putnam.
There are no federal limits on the amount of 4-methylimidazole in food and drink. The substance is formed in some caramel coloring at low levels during the manufacturing process. The FDA says it also can occur in trace amounts when coffee beans are roasted or some meats are grilled.
The Consumer Reports study urged the agency to set a maximum level of the substance when it is artificially added to foods or soda, to require labeling when it is added and to bar products from carrying the "natural" label if they contain caramel colors.
"There is no reason why consumers need to be exposed to this avoidable and unnecessary risk that can stem from coloring food and beverages brown," said Consumer Reports' Dr. Urvashi Rangan, a toxicologist and lead investigator on the study.
Though studies have not been conclusive about whether 4-methylimidazole is a carcinogen, California includes it on the state list of carcinogens and a state law mandates a cancer warning label on products that have a certain level of the substance. In reaction to that law, Coke, Pepsi and other soft drink makers have directed their caramel-color suppliers to reduce the levels of 4-methylimidazole. It is not found in all caramel colorings.
Over an eight-month period, the study found that single 12 oz. servings of two beverages purchased in California, Pepsi One and Malta Goya, exceeded the 29 micrograms of 4-methylimidazole that are the threshold per day in California but carried no warning. Consumer Reports has asked the California attorney general's office to investigate; a spokesman for the attorney general says the office is reviewing the request.
PepsiCo spokeswoman Aurora Gonzalez said the company is "extremely concerned" about the study and believes it is factually incorrect.
Gonzalez said the average amount of soda consumed daily by those who drink it is less than the 12-ounce can Consumer Reports used as its basis for measurement. As a result, she said people are not exceeding the limit of 29 micrograms a day.
But PepsiCo did not provide details about how it arrived at its conclusions of daily soda consumption.
"All of Pepsi's products are below the threshold set in California, and all are in full compliance with the law," she said.
A spokeswoman for the Centers for Disease Control and Prevention could not point to any recent data on daily consumption of all sodas, but Beverage Digest, a trade publication that tracks the industry, says per capita consumption of carbonated soft drinks in the U.S. is 1.3 cans of soda a day.
The drinks tested were Sprite, Diet Coke, Coca-Cola, Coke Zero, Dr Pepper, Dr. Snap, Brisk Iced Tea, A&W Root Beer, Pepsi, Diet Pepsi, Pepsi One and Goya Malta. Consumer Reports said there was no significant level found in Sprite, and consistently low levels were found in Coke products.
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